// Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module c

import v.ast

enum AssertMetainfoKind {
    pass
    fail
    panic
}

fn (mut g Gen) assert_stmt(original_assert_statement ast.AssertStmt) {
    if !original_assert_statement.is_used {
        return
    }
    mut node := original_assert_statement
    g.writeln('// assert')

    mut save_left := ast.empty_expr
    mut save_right := ast.empty_expr

    if mut node.expr is ast.InfixExpr {
        // Don't extract subexpressions to ctemps for && and || operators,
        // as this would break short-circuit evaluation semantics.
        // The right side of && must only execute after the left side is true.
        if node.expr.op !in [.and, .logical_or] {
            mut left_expr_type := node.expr.left_type
            mut right_expr_type := node.expr.right_type
            if g.cur_fn != unsafe { nil } && g.cur_concrete_types.len > 0 {
                resolved_left_type := g.resolved_expr_type(node.expr.left, node.expr.left_type)
                if resolved_left_type != 0 {
                    resolved_sym := g.table.sym(resolved_left_type)
                    left_sym := g.table.sym(left_expr_type)
                    if resolved_sym.kind !in [.sum_type, .interface]
                        || left_sym.kind in [.sum_type, .interface] {
                        left_expr_type = resolved_left_type
                    }
                }
                resolved_right_type := g.resolved_expr_type(node.expr.right, node.expr.right_type)
                if resolved_right_type != 0 {
                    resolved_sym := g.table.sym(resolved_right_type)
                    right_sym := g.table.sym(right_expr_type)
                    if resolved_sym.kind !in [.sum_type, .interface]
                        || right_sym.kind in [.sum_type, .interface] {
                        right_expr_type = resolved_right_type
                    }
                }
            }
            if subst_expr := g.assert_subexpression_to_ctemp(node.expr.left, left_expr_type) {
                save_left = node.expr.left
                node.expr.left = subst_expr
            }
            // For || and && operators, do not pre-evaluate the right side
            // to allow short-circuit evaluation to work correctly.
            if node.expr.op !in [.logical_or, .and] {
                if subst_expr := g.assert_subexpression_to_ctemp(node.expr.right, right_expr_type) {
                    save_right = node.expr.right
                    node.expr.right = subst_expr
                }
            }
        }
    }
    metaname := g.gen_assert_metainfo_common(node)
    g.set_current_pos_as_last_stmt_pos()
    g.inside_ternary++
    if g.pref.is_test {
        g.write('if (')
        prev_inside_ternary := g.inside_ternary
        g.inside_ternary = 0
        g.expr(node.expr)
        g.inside_ternary = prev_inside_ternary
        g.write(')')
        g.decrement_inside_ternary()
        g.writeln(' {')
        g.gen_assert_metainfo(node, .pass, metaname)
        g.writeln('\tmain__TestRunner_name_table[test_runner._typ]._method_assert_pass(test_runner._object, &${metaname});')
        g.writeln('} else {')
        g.gen_assert_metainfo(node, .fail, metaname)
        g.writeln('\tmain__TestRunner_name_table[test_runner._typ]._method_assert_fail(test_runner._object, &${metaname});')
        g.gen_assert_postfailure_mode(node)
        g.writeln('}')
    } else {
        g.write('if (!(')
        prev_inside_ternary := g.inside_ternary
        g.inside_ternary = 0
        g.expr(node.expr)
        g.inside_ternary = prev_inside_ternary
        g.write('))')
        g.decrement_inside_ternary()
        g.writeln(' {')
        g.gen_assert_metainfo(node, .panic, metaname)
        g.writeln('\tbuiltin____print_assert_failure(&${metaname});')
        g.gen_assert_postfailure_mode(node)
        g.writeln('}')
    }

    if mut node.expr is ast.InfixExpr {
        restore_left := node.expr.left is ast.CTempVar
        restore_right := node.expr.right is ast.CTempVar
        if restore_left {
            node.expr.left = save_left
        }
        if restore_right {
            node.expr.right = save_right
        }
    }
}

fn (mut g Gen) assert_subexpression_to_ctemp(expr ast.Expr, expr_type ast.Type) ?ast.Expr {
    match expr {
        ast.CallExpr {
            return g.new_ctemp_var_then_gen(expr, expr_type)
        }
        ast.ParExpr {
            if expr.expr is ast.CallExpr {
                return g.new_ctemp_var_then_gen(ast.Expr(expr.expr), expr_type)
            }
        }
        ast.PostfixExpr {
            return g.new_ctemp_var_then_gen(expr, expr_type)
        }
        ast.SelectorExpr {
            if expr.expr is ast.AsCast {
                mut subst_expr := expr
                as_cast_expr := expr.expr as ast.AsCast
                subst_expr.expr = ast.Expr(g.new_ctemp_var_then_gen(ast.Expr(as_cast_expr),
                    as_cast_expr.typ))
                return ast.Expr(subst_expr)
            }
            if expr.expr is ast.ParExpr && expr.expr.expr is ast.AsCast {
                mut subst_expr := expr
                as_cast_expr := expr.expr.expr as ast.AsCast
                subst_expr.expr = ast.Expr(g.new_ctemp_var_then_gen(ast.Expr(as_cast_expr),
                    as_cast_expr.typ))
                return ast.Expr(subst_expr)
            }
            if expr.expr is ast.CallExpr {
                sym := g.table.final_sym(g.unwrap_generic(expr.expr.return_type))
                if sym.kind == .struct {
                    if (sym.info as ast.Struct).is_union {
                        return none
                    }
                }
                return g.new_ctemp_var_then_gen(expr, expr_type)
            }
            if g.need_tmp_var_in_expr(expr) {
                return g.new_ctemp_var_then_gen(expr, expr_type)
            }
        }
        ast.LockExpr {
            return g.new_ctemp_var_then_gen(expr, expr_type)
        }
        ast.ArrayInit {
            if expr.has_callexpr || g.need_tmp_var_in_expr(expr) {
                return g.new_ctemp_var_then_gen(expr, expr_type)
            }
        }
        ast.StructInit {
            if g.need_tmp_var_in_expr(expr) {
                return g.new_ctemp_var_then_gen(expr, expr_type)
            }
        }
        else {
            if g.need_tmp_var_in_expr(expr) {
                return g.new_ctemp_var_then_gen(expr, expr_type)
            }
        }
    }

    return none
}

fn (mut g Gen) gen_assert_postfailure_mode(node ast.AssertStmt) {
    g.write_v_source_line_info_stmt(node)
    if g.pref.assert_failure_mode == .continues
        || g.fn_decl.attrs.any(it.name == 'assert_continues') {
        return
    }
    if g.pref.is_test && !g.inside_defer_generation && g.cur_fn != unsafe { nil }
        && g.cur_fn.scope != unsafe { nil } {
        g.write_defer_stmts_when_needed(g.innermost_active_defer_scope(node.pos), true, node.pos)
    }
    if g.pref.assert_failure_mode == .aborts || g.fn_decl.attrs.any(it.name == 'assert_aborts') {
        g.writeln('\tabort();')
    }
    if g.pref.assert_failure_mode == .backtraces
        || g.fn_decl.attrs.any(it.name == 'assert_backtraces') {
        if _ := g.table.fns['print_backtrace'] {
            g.writeln('\tbuiltin__print_backtrace();')
        }
    }
    if g.pref.is_test {
        g.writeln('\tlongjmp(g_jump_buffer, 1);')
    }
    if g.pref.assert_failure_mode != .continues {
        g.writeln('\tbuiltin___v_panic(_S("Assertion failed..."));')
    }
}

fn (mut g Gen) gen_assert_metainfo(node ast.AssertStmt, kind AssertMetainfoKind, metaname string) {
    if kind == .pass {
        return
    }
    if node.extra is ast.EmptyExpr {
        g.writeln('\t${metaname}.has_msg = false;')
        g.writeln('\t${metaname}.message = _SLIT0;')
    } else {
        g.writeln('\t${metaname}.has_msg = true;')
        g.write('\t${metaname}.message = ')
        g.gen_assert_single_expr(node.extra, ast.string_type)
        g.writeln(';')
    }
    match node.expr {
        ast.InfixExpr {
            mut left_type := if node.expr.left_ct_expr {
                g.type_resolver.get_type_or_default(node.expr.left, node.expr.left_type)
            } else {
                node.expr.left_type
            }
            mut right_type := if node.expr.right_ct_expr {
                g.type_resolver.get_type(node.expr.right)
            } else {
                node.expr.right_type
            }
            if g.cur_fn != unsafe { nil } && g.cur_concrete_types.len > 0 {
                resolved_left := g.resolved_expr_type(node.expr.left, node.expr.left_type)
                if resolved_left != 0 {
                    resolved_sym := g.table.sym(resolved_left)
                    left_sym := g.table.sym(left_type)
                    if resolved_sym.kind !in [.sum_type, .interface]
                        || left_sym.kind in [.sum_type, .interface] {
                        left_type = resolved_left
                    }
                }
                resolved_right := g.resolved_expr_type(node.expr.right, node.expr.right_type)
                if resolved_right != 0 {
                    resolved_sym := g.table.sym(resolved_right)
                    right_sym := g.table.sym(right_type)
                    if resolved_sym.kind !in [.sum_type, .interface]
                        || right_sym.kind in [.sum_type, .interface] {
                        right_type = resolved_right
                    }
                }
            }
            g.write('\t${metaname}.lvalue = ')
            g.gen_assert_single_expr(node.expr.left, left_type)
            g.writeln(';')
            // For && and || operators, use a placeholder for rvalue
            // to avoid issues with go_before_last_stmt() which can generate
            // temporary variables outside the conditional scope.
            // - For &&: if left is false, right is short-circuited
            // - For ||: if left is true, right is short-circuited
            if node.expr.op in [.logical_or, .and] {
                g.writeln('\t${metaname}.rvalue = _S("<short-circuited>");')
            } else {
                g.write('\t${metaname}.rvalue = ')
                g.gen_assert_single_expr(node.expr.right, right_type)
                g.writeln(';')
            }
        }
        else {}
    }
}

fn (mut g Gen) gen_assert_metainfo_common(node ast.AssertStmt) string {
    mod_path := cestring(g.file.path)
    fn_name := g.fn_decl.name
    line_nr := node.pos.line_nr
    mut src := node.expr.str()
    if node.extra !is ast.EmptyExpr {
        src += ', ' + node.extra.str()
    }
    src = cestring(src)
    metaname := 'v_assert_meta_info_${g.new_tmp_var()}'
    g.writeln('VAssertMetaInfo ${metaname} = {0};')
    g.writeln('${metaname}.fpath = ${ctoslit(mod_path)};')
    g.writeln('${metaname}.line_nr = ${line_nr};')
    g.writeln('${metaname}.fn_name = ${ctoslit(fn_name)};')
    metasrc := cnewlines(ctoslit(src))
    g.writeln('${metaname}.src = ${metasrc};')
    g.writeln('${metaname}.has_msg = false;')
    match node.expr {
        ast.InfixExpr {
            expr_op_str := ctoslit(node.expr.op.str())
            expr_left_str := cnewlines(ctoslit(node.expr.left.str()))
            expr_right_str := cnewlines(ctoslit(node.expr.right.str()))
            g.writeln('${metaname}.op = ${expr_op_str};')
            g.writeln('${metaname}.llabel = ${expr_left_str};')
            g.writeln('${metaname}.rlabel = ${expr_right_str};')
        }
        ast.CallExpr {
            g.writeln('${metaname}.op = _S("call");')
        }
        else {}
    }

    return metaname
}

fn (mut g Gen) gen_assert_single_expr(expr ast.Expr, typ ast.Type) {
    // eprintln('> gen_assert_single_expr typ: ${typ} | expr: ${expr} | typeof(expr): ${typeof(expr)}')
    expr_str := '${expr}'
    match expr {
        ast.CastExpr {
            if typ.is_float() || g.table.final_sym(typ).is_float() {
                g.gen_expr_to_string(expr.expr, typ)
            } else {
                g.write(ctoslit(expr_str))
            }
        }
        ast.ParExpr {
            g.gen_assert_single_expr(expr.expr, typ)
        }
        ast.IfExpr, ast.MatchExpr, ast.RangeExpr {
            g.write(ctoslit(expr_str))
        }
        ast.IndexExpr {
            g.gen_expr_to_string(expr, typ)
        }
        ast.PrefixExpr {
            if expr.right is ast.CastExpr {
                // TODO: remove this check;
                // vlib/builtin/map_test.v (a map of &int, set to &int(0)) fails
                // without special casing ast.CastExpr here
                g.write(ctoslit(expr_str))
            } else if expr.right is ast.Ident {
                g.write(ctoslit(expr_str))
            } else {
                g.gen_expr_to_string(expr, typ)
            }
        }
        ast.TypeNode {
            sym := g.table.sym(g.unwrap_generic(typ))
            g.write(ctoslit('${sym.name}'))
        }
        else {
            mut should_clone := true
            if typ == ast.string_type
                && expr in [ast.IndexExpr, ast.CallExpr, ast.StringLiteral, ast.StringInterLiteral] {
                should_clone = false
            }
            if expr is ast.CTempVar && expr.orig is ast.CallExpr {
                should_clone = false
                if expr.orig.or_block.kind == .propagate_option {
                    should_clone = true
                }
                if expr.orig.is_method && expr.orig.args.len == 0 && expr.orig.name == 'type_name' {
                    should_clone = true
                }
            }
            if should_clone {
                g.write('builtin__string_clone(')
            }
            g.gen_expr_to_string(expr, typ)
            if should_clone {
                g.write(')')
            }
        }
    }
}